Recently, as air pollution problems have been aggravated, research into development of alternative energy has been actively conducted to find a solution in terms of the protection of environment. Battery systems have been developed as development of alternative energy, for example, characteristics of lithium secondary batteries has been improved.
Negative electrodes of lithium secondary batteries have been manufactured largely with graphite, but low ion capacity of about 372 mAh/g per weight (gram) has been a limitation in improving characteristics of lithium secondary batteries. Thus, research has recently continued to manufacture negative electrodes with silicon having ion capacity of about 4,000 mAh/g and lithium metal having ion capacity of about 3,860 mAh/g.
Manufacturing a negative electrode with lithium metal may implement high capacity lithium secondary batteries, but non-uniform desorption/adsorption of lithium in a process in which lithium secondary batteries are repeatedly charged and discharged may lead to formation of lithium having an acicular structure (dendrite) on a surface of the negative electrode. When lithium having the acicular structure continues to grow, it may penetrate through a separator within a battery to reach a positive electrode to cause internal short, battery explosion, and the like.
In order to solve the above-mentioned problem in the related arts, various attempts have been made to restrain formation of lithium having an acicular structure by increasing a surface area of a negative electrode formed of lithium metal but not reached a satisfactory level yet.